Technical field
Embodiments of the present invention generally relates to an image forming apparatus and an image forming method.
Related Art
There has been known an image forming apparatus that outputs a transfer bias (transfer current) in which a direct current (DC) voltage and an alternating current (AC) voltage are superimposed on each other to a transfer nip formed by an image bearer contacting a nip forming member, thereby transferring a toner image from a surface of the image bearer onto a recording sheet in the transfer nip.
In an image forming apparatus, for example, a secondary-transfer power source outputs a secondary-transfer bias as intruder current to a secondary-transfer nip formed by a nip forming roller as a nip forming member contacting an intermediate transfer belt as the image bearer. The secondary-transfer power source outputs a secondary-transfer bias including only the DC voltage to transfer a toner image from the intermediate transfer belt onto a recording sheet without unevenness on the surface thereof. However, the secondary-transfer power source outputs a superimposed voltage, in which the AC voltage is superimposed on the DC voltage, as the secondary-transfer bias to form an alternating electrical field within the secondary-transfer nip to transfer the toner image from the intermediate transfer belt onto a recording sheet, with an uneven surface, such as Japan paper. Such a generated alternating electrical field reciprocates toner between the surface of the intermediate transfer belt and the recesses on the surface of the recording sheet in the secondary-transfer nip, thereby secondarily transferring toner onto the recesses on the surface of the recording sheet, in a successful manner.